Controlling Factors on Oil and Gas Accumulation and Accumulation Modes of the Paleogene “Red Bed” in the South Slope of the Dongying Depression, China

Abstract

The Paleogene “Red Bed”, the alternative strata for oil and gas exploration in the South Slope of the Dongying Depression, refers to a set of red clastic sediments of the lower 4th member of the Shahejie Formation and the 1st member of the Kongdian Formation. And it has important significance to study the controlling factors on oil and gas accumulation and the accumulation modes for guiding the deep-layer oil and gas exploration in the area. In this paper, according to the statistics of oil and gas static characteristics, analysis of oil original types, study of pathway system and recovery of oil and gas accumulation, the controlling factors on the Red Bed oil and gas accumulation were summarized as follows: source rock controlling oil and gas distribution, physical features of reservoir bed controlling trap oiliness, faults controlling oil and gas source and trap conditions, and nose structural zone controlling oil and gas migration and enrichment zone. Based on these studies, three accumulation modes for the Paleogene Red Bed in the research area were built: joints of source rock and reservoir bed acting as lateral pathway for oil and gas accumulation, faults acting as vertical pathway for oil and gas accumulation, and high pressure of deeper depression resulting in oil and gas flowing downward to form accumulation.